1. Field of the Invention
The present invention relates to a steering module including a non-rotative pad attached to a central portion of a steering wheel.
The present application is based on Japanese Patent Application No. Hei. 9-321406, which is incorporated herein by reference.
2. Description of the Related Art
In recent years, a variety of switches for controlling a driving operation and operating audio units have intensively been mounted on a pad attached to a central portion of a steering wheel in addition to the horn switch. To improve the operability and visibility of the switches, a variety of steering wheel apparatuses have been suggested each of which has a structure that the pad is secured to the car body portion to inhibit rotation of the pad.
As an example of a steering wheel apparatus of the foregoing type, a structure disclosed in, for example, Unexamined Japanese Utility Model Publication No. Sho. 60-69752 will now be described with reference to FIG. 6. FIG. 6 is an exploded perspective view showing a steering wheel apparatus.
A housing 1 is secured to a steering column (not shown). A first substrate 3 is secured to the housing 1. A steering shaft 5 passes through a central portion of the housing 1 and a central portion of the first substrate 3. An external gear 7 is secured to a leading end of the steering shaft 5.
An annular internal gear 13 is connected to a steering wheel 9 through a spoke 11. The internal gear 13 is accommodated in the housing 1 such that the internal gear 13 surrounds the external gear 7. The internal gear 13 is rotatably accommodated in the housing 1 by a second substrate 15 secured to a position apart from the first substrate 3.
An intermediate gear 17, which is engaged with the external gear 7 and the internal gear 13, is rotatably supported by the first substrate 3. A pad substrate 19 having operation switches and a variety of electric devices is secured to the second substrate 15. The pad substrate 19 is covered by a cover 21 so that a pad 23 is formed. The first substrate 3 and the second substrate 15 have through holes 25 and 27. The through holes 25 and 27 are formed to penetrate a wire harness 29 which is connected to the pad substrate 19 and extending from the car body portion.
The steering wheel apparatus has the above-mentioned structure in that the pad 23 is secured to the car body portion through the housing 1, the first substrate 3 and the second substrate 15. Thus, the pad 23 is made to be non-rotative. When the steering shaft 5 is rotated through the internal gear 13, the intermediate gear 17 and the external gear 7 because the steering wheel 9 has been rotated, the pad 23 maintains a stationary state. Therefore, the operability and visibility of the switches and so forth can be improved.
However, the above-mentioned steering wheel apparatus has the structure that the plural through holes are formed in the first and second substrates. Moreover, the wire harness extending from the car body portion is caused to penetrate the housing, the first substrate, the internal gear and the second substrate so as to be connected to a connector mounted on the pad substrate. Therefore, the wire harness must be caused to penetrate the foregoing components whenever the component is assembled. If a plurality of wire harnesses are provided, many penetrating operations must be performed. As a result, the workability of the assembling operation deteriorates.
Since the wire harness is caused to penetrate the foregoing components, the length of wire harness must have a somewhat great slack as compared with the length after the assembling operation has been completed. When the wire harness having the foregoing slack is allowed to pass through the internal gear which is rotated, there is apprehension that, for example, the wire harness is bit by the internal gear owning to looseness.